Rotary damper with self-standing mechanism

ABSTRACT

A rotary damper for use with a toilet lid has a damper shaft rotatably supported by a damper housing, a collar of synthetic resin fitted over the damper shaft for rotation therewith, and a casing of synthetic resin fixed to the damper housing and disposed around the collar for rotation relative thereto. The collar has a pair of diametrically opposite axial ridges disposed on the outer circumferential surface thereof and projecting radially outwardly. The casing has a pair of diametrically opposite cantilevered resilient arms defined by respective slits in the circumferential wall thereof. The cantilevered resilient arms have respective axial teeth disposed on the inner circumferential surface of the casing and projecting radially inwardly for engagement with the axial ridges, respectively. When the collar rotates in one direction, respective slanting surfaces of the axial ridges engage and move over the respective axial teeth, displacing the axial teeth radially outwardly against the resiliency of the cantilevered resilient arms. After the axial ridges move past the respective axial teeth, respective step surfaces of the axial ridges are locked by the axial teeth, retaining the collar and hence the damper shaft in a rotated position unless strong forces are applied to rotate the damper shaft backward.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotary damper for use with a toiletlid or a similar angularly movable lid, and more particularly to aself-standing mechanism in such a rotary damper for keeping an angularlymovable lid in an upright position against falling movement by gravity.

2. Description of the Prior Art

One known rotary damper with a self-standing mechanism is disclosed inJapanese laid-open patent publication No. 5-180239.

The disclosed rotary damper, which is typically used with a toilet lid,has a cylindrical casing which houses a pair of spring-biased balls anda rotor rotatably disposed in the cylindrical casing and having a pairof diametrically opposite recesses for receiving the spring-biasedballs, respectively. The rotor has an axial end coupled to a shaft ofthe toilet lid. A viscous fluid is sealed in a space between thecylindrical casing and the rotor for damping angular movement of therotor with respect to the cylindrical casing.

When the toilet lid is manually opened to its upright position by theuser, the rotor is angularly moved in one direction about its own axisuntil the spring-biased balls are received in the recesses,respectively. The spring-biased balls received in the respectiverecesses retain the toilet lid in the upright position, typically 90°spaced upwardly from the toilet seat on the toilet bowl.

When the toilet lid is manually closed from the upright position by theuser, the spring-biased balls are forced out of the respective recesses,and the toilet lid is slowly angularly moved downwardly toward thetoilet seat under damping forces produced by the viscous fluid. At thetime the spring-biased balls are forced out of the respective recesses,the spring-biased balls frictionally engage edges of the recesses. Asthe toilet lid is repeatedly opened and closed, the edges of therecesses tend to wear off to a round shape by frictional contact withthe spring-biased balls. The round edges of the recesses are ineffectiveto retain the spring-biased balls firmly in the respective recesses, andhence to hold the toilet lid in the upright position.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a rotarydamper with a self-standing mechanism which is subject to a relativelysmall rate of wear and can hold an angularly movable lid firmly in anupright position.

Another object of the present invention is to provide a rotary damperwith a self-standing mechanism which is made up of a relatively smallnumber of parts, has a relatively small size, can be assembledrelatively easily, and can be manufactured relatively inexpensively.

According to the present invention, there is provided a rotary dampercomprising a damper housing, a damper shaft rotatably supported by thedamper housing, a collar of synthetic resin fitted over the damper shaftfor rotation therewith, and a casing of synthetic resin fixed to thedamper housing and disposed around the collar for rotation relativethereto, the collar having at least one axial ridge disposed on an outercircumferential surface thereof and projecting radially outwardly, thecasing having at least one cantilevered resilient arm defined by a slitin a circumferential wall thereof, the cantilevered resilient arm havingan axial tooth disposed on an inner circumferential surface of thecasing and projecting radially inwardly for engagement with the axialridge.

The axial ridge may have a step surface extending from a ridge crestradially inwardly to the outer circumferential surface of the casing inone circumferential direction, and a slanting surface extending from theridge crest radially inwardly to the outer circumferential surface ofthe casing in an opposite circumferential direction. The step surfacemay be inclined to the outer circumferential surface of the casing at anangle which is greater than an angle at which the slanting surface isinclined to the outer circumferential surface of the casing.

Preferably, the collar may have a pair of diametrically opposite axialridges disposed on the outer circumferential surface thereof andprojecting radially outwardly, and the casing may have a pair ofdiametrically opposite cantilevered resilient arms defined by respectiveslits in the circumferential wall thereof, the cantilevered resilientarms having respective axial teeth disposed on the inner circumferentialsurface of the casing and projecting radially inwardly for engagementwith the axial ridges, respectively.

According to the present invention, there is also provided a rotarydamper comprising a damper housing, a damper shaft rotatably supportedby the damper housing, a collar of synthetic resin fitted over thedamper shaft for rotation therewith, and a casing of synthetic resinfixed to the damper housing and disposed around the collar for rotationrelative thereto, the collar having at least one cantilevered resilientarm defined by a slit in a circumferential wall thereof, thecantilevered resilient arm having an axial tooth disposed on an outercircumferential surface of the collar and projecting radially outwardly,the casing having at least one axial ridge disposed on an innercircumferential surface thereof and projecting radially inwardly forengagement with the axial ridge.

According to the present invention, there is further provided a rotarydamper comprising a damper housing, a damper shaft rotatably supportedby the damper housing, the damper shaft having at least one first axialgroove defined in an outer circumferential surface thereof, a collarfixed to the damper housing and disposed around the damper shaft forrotation relative thereto, the collar having at least one second axialgroove defined in a circumferential wall thereof, at least one firstneedle disposed in the first groove and having a portion projectingradially outwardly from the outer circumferential surface of the dampershaft, and at least one second needle disposed in the second groove, andan annular spring resiliently fitted over the collar and held againstthe second needle for resiliently pushing the second needle partly outof the second groove for engagement with the first needle.

Each of the first needle and the second needle may be made of metal.

The annular spring may have a slot defined in a portion thereof andextending fully axially thereacross, the collar having an axial stopperprojecting radially outwardly and fitted in the slot. The annular springmay have a pair of resilient wings extending circumferentially one oneach side of a fulcrum region of the annular spring that is positioneddiametrically opposite to the slot, the resilient wings beingprogressively tapered off toward the slot.

The damper shaft may have a plurality of first axial grooves defined inthe outer circumferential surface thereof, and the collar has aplurality of second axial grooves defined in the circumferential wallthereof, and the rotary damper may further comprise a plurality of firstneedles disposed in the first grooves, respectively, and havingrespective portions projecting radially outwardly from the outercircumferential surface of the damper shaft, and a plurality of secondneedles disposed in the second grooves, respectively. Specifically, thedamper shaft may have a pair of diametrically opposite first axialgrooves defined in the outer circumferential surface thereof, and thecollar may have a pair of diametrically opposite second axial groovesdefined in the circumferential wall thereof, further comprising a pairof diametrically opposite first needles disposed in the first grooves,respectively, and having respective portions projecting radiallyoutwardly from the outer circumferential surface of the damper shaft,and a pair of diametrically opposite second needles disposed in thesecond grooves, respectively.

The above and further objects, details and advantages of the presentinvention will become apparent from the following detailed descriptionof preferred embodiments thereof, when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a rotary damper according to afirst embodiment of the present invention;

FIG. 2 is an enlarged transverse cross-sectional view of the rotarydamper shown in FIG. 1;

FIG. 2A is an enlarged fragmentary transverse cross-sectional view of amodified rotary damper;

FIG. 3 is a plan view, partly cut away, showing the rotary damper thatis coupled to a toilet lid;

FIG. 4 is an exploded perspective view of a rotary damper according to asecond embodiment of the present invention;

FIG. 5 is an enlarged transverse cross-sectional view of the rotarydamper shown in FIG. 4; and

FIG. 6 is a view similar to FIG. 5, showing the rotary damper in anoperative position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a rotary damper 10 according to a first embodimentof the present invention has a substantially cylindrical damper housing12 which supports a damper shaft 14 rotatably therein. The damperhousing 12 accommodates therein a suitable damping medium such as aviscous fluid which acts between the damper housing 12 and a portion ofthe damper shaft 14 which is disposed in the damper housing 12. Thedamping medium applies a damping torque to the damper shaft 14 when thedamper shaft 14 rotates in one direction about its own axis with respectto the damper housing 12. Such a damping action of the damping medium iswell known in the art.

The damper shaft 14 also has a portion projecting out of the damperhousing 12 and having a pair of diametrically opposite flat walls 16extending axially of the damper shaft 14. The projecting portion of thedamper shaft 14 has a hollow space 18 that receives therein a rotatableshaft 20, typically a shaft projecting from a toilet seat, which issnugly fitted in the hollow space 18. The rotatable shaft 20 has a pairof diametrically opposite flat walls 22 on its outer circumferentialsurface which extend in its axial direction. The flat walls 22 of therotatable shaft 20 are positioned radially inwardly of and held firmlyagainst the respective flat walls 16 of the damper shaft 14.Consequently, when the rotatable shaft 20 rotates, the damper shaft 14rotates in unison with the rotatable shaft 20.

The rotary damper 10 also includes a cylindrical collar 24 molded ofsynthetic resin which has a pair of diametrically opposite flat walls26. The collar 24 is press-fitted over the damper shaft 14 with the flatwalls 26 positioned radially outwardly of and held firmly against therespective flat walls 16 of the damper shaft 14.

The collar 24 has a pair of diametrically opposite arcuate walls 28extending between the flat walls 26. The arcuate walls 28 haverespective axial ridges 30 (see also FIG. 2) positioned in diametricallyopposite relationship to each other and projecting radially outwardlyaway from each other. Each of the axial ridges 30 has a step surface 30aextending from a ridge crest radially inwardly to the outercircumferential surface of the arcuate wall 28 in one circumferentialdirection and a slanting surface 30b extending from the ridge crestradially inwardly to the outer circumferential surface of the arcuatewall 28 in the opposite circumferential direction. The angle at whichthe step surface 30a is inclined to the outer circumferential surface ofthe arcuate wall 28 is greater than the angle at which the slantingsurface 30b is inclined to the outer circumferential surface of thearcuate wall 28.

A cylindrical casing 32 molded of synthetic resin is loosely fitted overthe collar 24 and fastened to an end surface 12a of the damper housing12 by screws 12b that are threaded through respective tongues 12c on thecasing 32 into screw holes 12d defined in the end surface 12a of thedamper housing 12.

As shown in FIGS. 1 and 2, the casing 32 has a pair of diametricallyopposite channel-shaped slits 34 defined in its cylindrical wall,forming a pair of diametrically opposite cantilevered resilient arms 36surrounded by the slits 34. The cantilevered resilient arms 36 haverespective integrally formed teeth 38 positioned on their free ends andextending in the axial direction of the casing 32, the teeth 38projecting radially inwardly from the inner circumferential surface ofthe casing 32 for sliding engagement with the respective axial ridges 30on the collar 24.

In the above embodiment, the collar 24 has the ridges 30 and the casing32 has the cantilevered resilient arms 36. However, as shown in FIG. 2A,the collar 24' may have cantilevered resilient arms 36' with teeth 38'(only one shown), defined by slits 34' and the casing 32' may haveridges 30' (only one shown).

The ridges 30 on the collar 24 and the teeth 38 on the casing 32 jointlyserve as a self-standing mechanism as described later on.

As shown in FIG. 3, the rotary damper 10 is typically used incombination with a toilet lid 1 which incorporates the rotatable shaft20 as one of its shafts.

When the toilet lid 1 is manually lifted open away from the toilet seat(not shown), the rotatable shaft 20 rotates counterclockwise in thedirection indicated by the arrow A (FIG. 2), and the damper shaft 14also rotates in the same direction. Since the collar 24 is press-fittedover the damper shaft 14, the collar 24 also rotates counterclockwise inthe direction indicated by the arrow A.

Upon continued counterclockwise rotation of collar 24 in the directionindicated by the arrow A, the slanting surfaces 30b of the ridges 30slidingly engage and then push the respective teeth 38 radiallyoutwardly, elastically deforming the cantilevered resilient arms 36gradually in the radially outward direction. When the slanting surfaces30b move over the crests of the teeth 38, the teeth 38 snap backradially inwardly against the step surfaces 30a of the ridges 30 underthe resiliency of the cantilevered resilient arms 36. The ridges 30 andthe teeth 38 are now held in engagement with each other, respectively,as shown in FIG. 2. Since the step surfaces 30a are locked in engagementwith the corresponding teeth 38, the collar 24 and hence the dampershaft 14 are prevented from rotating back clockwise in the directionindicated by the arrow B. Consequently, the toilet lid 1 is retained inan upright position with respect to the toilet seat by the self-standingmechanism.

While the toilet lid 1 is being lifted from the toilet seat toward theupright position, the damping medium in the housing 12 does not exert adamping torque to the damper shaft 14. Therefore, the damper shaft 14can quickly be rotated, allowing the toilet lid 1 to be lifted quickly.

When the toilet lid 1 is manually lowered from the upright positiontoward the toilet seat, the damper shaft 14 and hence the collar 24 arerotated clockwise in the direction indicated by the arrow B. The stepsurfaces 30a of the collar 24 force the teeth 38 to move radiallyoutwardly against the resiliency of the cantilevered resilient arms 36as they are elastically deformed radially outwardly. The step surfaces30a now move over the crests of the teeth 38, which then snap backradially inwardly against the slanting surfaces 30b. Once the ridges 30move past the teeth 38, the toilet lid 1 can easily be lowered towardthe toilet seat.

While the toilet lid 1 is being lowered from the upright position towardthe toilet seat, the damping medium in the housing 12 exerts a dampingtorque to the damper shaft 14. Therefore, the rotation of the dampershaft 14 and hence the collar 24 is slowed, and the toilet lid 1 isslowly lowered even under gravity.

The toilet lid 1 can be lifted into the upright position relativelysmoothly and quickly with relatively little manual force because nodamping action is applied and the teeth 38 are pushed radially outwardlyby the slanting surfaces 30b. Once the toilet lid 1 is in the uprightposition, it is reliably retained in the upright position by the stepsurfaces 30a held in engagement with the teeth 38. The toilet lid 1 canbe lowered from the upright position less smoothly and quickly than whenit is lifted into the upright position because relatively large manualforce needs to be applied to move the step surfaces 30a out of lockingengagement with the teeth 38.

Since the teeth 38 are disposed on the cantilevered resilient arms 36,the teeth 38 and the ridges 30 are prevented from being held in unduefrictional engagement with each other, and hence from being worn undulysoon during usage.

In addition, the rotary damper 10 is made up of a relatively smallnumber of parts, has a relatively small size, can be assembledrelatively easily, and hence can be manufactured relativelyinexpensively.

FIGS. 4 through 6 show a rotary damper 100 according to a secondembodiment of the present invention.

As shown in FIG. 4, the rotary damper 100 has a cylindrical damperhousing 112 which supports a damper shaft 114 rotatably therein. Thedamper housing 112 accommodates therein a suitable damping medium whichexerts a damping torque to the damper shaft 114 when the damper shaft114 rotates in one direction about its own axis with respect to thedamper housing 112 in the same manner as with the rotary damper 10according to the first embodiment of the present invention.

The damper shaft 114 has a portion projecting out of the damper housing112 and having an axial hole 116 defined therein partly by a flat wall120. The axial hole 116 receives therein a rotatable shaft 118,typically a shaft projecting from a toilet seat, which is snugly fittedin the axial hole 116. The rotatable shaft 118 has a flat wall 122extending in its axial direction. The flat wall 122 of the rotatableshaft 118 is positioned radially inwardly of and held firmly against theflat wall 120 of the damper shaft 114. Consequently, when the rotatableshaft 118 rotates, the damper shaft 114 rotates in unison with therotatable shaft 118.

The damper shaft 114 may have an axial extension with a flat wall,rather than the axial hole 116, and the rotatable shaft 118 may have anaxial hole defined therein partly by a flat wall, rather than the flatwall 122, so that the axial extension may be fitted in the axial holefor corotation of the damper shaft 114 and the rotatable shaft 118.

The axial hole 116 may have a polygonal cross-sectional shape such as ahexagonal cross-sectional shape, and the rotatable shaft 118 may alsohave a complementary polygonal cross-sectional shape such as a hexagonalcross-sectional shape, so that the rotatable shaft 118 may be fitted inthe axial hole 116 for rotation with the damper shaft 114.

The damper shaft 114 has a pair of diametrically opposite first grooves124 defined in its outer circumferential surface and extending axiallyof the damper shaft 114. The first grooves 124 receive respective firstneedles 126, preferably made of metal, having a circular cross sectionand extending axially of the damper shaft 114. The first needles 126have substantially half portions fitted or embedded in the respectivefirst grooves 124, such that the other half portions of the firstneedles 126 project radially outwardly from the outer circumferentialsurface of the damper shaft 114.

The rotary damper 100 also includes a cylindrical collar 130 which has apair of diametrically opposite second grooves 132 defined in itscircumferential wall and extending in the axial direction thereof. Thecollar 130 is loosely fitted over the damper shaft 114 and fixed at anaxial end thereof to the damper housing 112. Second needles 134,preferably made of metal, having a circular cross section extend axiallyof the collar 130 and are loosely or radially movably fitted in therespective second grooves 132. The collar 130 has a stopper 136 of acertain width extending in the axial direction thereof and projectingradially outwardly between the second grooves 132.

An annular spring 140, which comprises a leaf-spring ring in theillustrated embodiment, is resiliently fitted over the collar 130 (seealso FIGS. 5 and 6) against the second needles 134, resiliently pushingthe second needles 134 so as to project radially inwardly partly out ofthe second grooves 132. The annular spring 140 has a slot 142 defined ina lower portion thereof and extending fully axially across the annularspring 140. The annular spring 140 has a pair of resilient wings 146extending circumferentially one on each side of a fulcrum region 144that is positioned diametrically opposite to the slot 142. The resilientwings 146 are progressively tapered off toward the slot 142 fordispersing stresses which would otherwise tend to concentrate on thefulcrum region 144 when the resilient wings 146 are resiliently spreadradially outwardly as described later on. Since such stresses aredispersed by the tapered resilient wings 146, the annular spring 140 ishighly durable in use.

The annular spring 140 is made of spring steel. The annular spring 140may comprise a wire-spring ring or a coil spring, rather than theleaf-spring ring.

The first needles 124 received in the first grooves 124, the secondneedles 134 received in the second grooves 132, and the annular spring140 jointly make up a self-standing mechanism.

As shown in FIG. 5, the stopper 136 of the collar 130 is fitted in theslot 142 in the annular spring 140, i.e., the opposite ends of theannular spring 140 are held against the opposite sides, respectively, ofthe stopper 136. Therefore, the annular spring 140 is prevented fromrotating relatively to the collar 130. The collar 130 may have a stopridge or stop ridges on the outer circumferential surface thereof at anend thereof remote from the damper housing 112 for retaining the annularspring 140 on the collar 130.

When a toilet lid connected to the damper shaft 114 by the rotatableshaft 118 is manually lifted open away from its corresponding toiletseat, the damper shaft 114 rotates counterclockwise in the directionindicated by the arrow A (FIG. 5), and the projecting half portions ofthe first needles 126 are brought into contact with the portions of thesecond needles 134 which project radially inwardly out of the respectivesecond grooves 132. Continued rotation of the damper shaft 114 causesthe first needles 126 to push the second needles 134 radially outwardlyagainst the resiliency of the annular spring 140, whereupon theresilient wings 146 of the annular spring 140 are elastically deformedapart radially outwardly about the fulcrum region 144 as shown in FIG.6. The damper shaft 114 is continuously rotated until the first needles126 move over the second needles 134, which then snap back radiallyinwardly under the bias of the annular spring 140. The first needles 126engage the second needles 134, preventing the damper shaft 114 fromrotating back clockwise. At this time, the toilet lid is retained in itsupright position by the self-standing mechanism.

The toilet lid remains in its upright position unless it is manuallylowered toward the toilet seat under forces large enough to rotate thedamper shaft 114 in the direction indicated by the arrow B to enable thefirst needles 126 to forcibly displace the second needles 134 radiallyoutwardly against the bias of the annular spring 146.

While the first needles 124 and the second needles 134 are positioned indiametrically opposite relationship, i.e., 180° spaced apart, in theillustrated embodiment, the first needles 124 and the second needles 134may be provided in two respective sets of pairs that are 90° spacedapart since the toilet lid is usually required to be angularly moved 90°from the toilet seat to the upright position and back. Alternatively,the first needles 124 and the second needles 134 may be provided infreely selected angularly spaced positions to retain the damper shaft 14in a freely selected angular position with respect to the damper housing112.

Although there have been described what are at present considered to bethe preferred embodiments of the invention, it will be understood thatthe invention may be embodied in other specific forms without departingfrom the essential characteristics thereof. The present embodiments aretherefore to be considered in all respects as illustrative, and notrestrictive. The scope of the invention is indicated by the appendedclaims rather than by the foregoing description.

What is claimed is:
 1. A rotary damper comprising:a damper housing; adamper shaft rotatably supported by said damper housing, said dampershaft having at least one first axial groove defined in an outercircumferential surface thereof; a collar fixed to said damper housingand disposed around said damper shaft for rotation relative thereto,said collar having at least one second axial groove defined in acircumferential wall thereof; at least one first needle disposed in saidfirst groove and having a portion projecting radially outwardly from theouter circumferential surface of said damper shaft; and at least onesecond needle disposed in said second groove; and an annular springresiliently fitted over said collar and held against said second needlefor resiliently pushing said second needle partly out of said secondgroove for engagement with said first needle.
 2. A rotary damperaccording to claim 1, wherein each of said first needle and said secondneedle is made of metal.
 3. A rotary damper according to claim 2,wherein said annular spring has a slot defined in a portion thereof andextending fully axially thereacross, said collar having an axial stopperprojecting radially outwardly and fitted in said slot.
 4. A rotarydamper according to claim 3, wherein said annular spring has a pair ofresilient wings extending circumferentially one on each side of afulcrum region of the annular spring that is positioned diametricallyopposite to said slot.
 5. A rotary damper according to claim 4, whereinsaid resilient wings are progressively tapered off toward said slot. 6.A rotary damper according to claim 2, wherein said damper shaft has aplurality of first axial grooves defined in the outer circumferentialsurface thereof, and said collar has a plurality of second axial groovesdefined in the circumferential wall thereof, further comprising aplurality of first needles disposed in said first grooves, respectively,and having respective portions projecting radially outwardly from theouter circumferential surface of said damper shaft, and a plurality ofsecond needles disposed in said second grooves, respectively.
 7. Arotary damper according to claim 6, wherein said damper shaft has a pairof diametrically opposite first axial grooves defined in the outercircumferential surface thereof, and said collar has a pair ofdiametrically opposite second axial grooves defined in thecircumferential wall thereof, further comprising a pair of diametricallyopposite first needles disposed in said first grooves, respectively, andhaving respective portions projecting radially outwardly from the outercircumferential surface of said damper shaft, and a pair ofdiametrically opposite second needles disposed in said second grooves,respectively.